We are an ecosystem!!

Viruses in the faecal microbiota of monozygotic twins and their mothers. 
Reyes A, Haynes M, Hanson N, Angly FE, Heath AC, Rohwer F, Gordon JI.

Abstract

Viral diversity and life cycles are poorly understood in the human gut and other body habitats. Phages and their encoded functions may provide informative signatures of a human microbiota and of microbial community responses to various disturbances, and may indicate whether community health or dysfunction is manifest after apparent recovery from a disease or therapeutic intervention. Here we report sequencing of the viromes (metagenomes) of virus-like particles isolated from faecal samples collected from healthy adult female monozygotic twins and their mothers at three time points over a one-year period. We compared these data sets with data sets of sequenced bacterial 16S ribosomal RNA genes and total-faecal-community DNA. Co-twins and their mothers share a significantly greater degree of similarity in their faecal bacterial communities than do unrelated individuals. In contrast, viromes are unique to individuals regardless of their degree of genetic relatedness. Despite remarkable interpersonal variations in viromes and their encoded functions, intrapersonal diversity is very low, with >95% of virotypes retained over the period surveyed, and with viromes dominated by a few temperate phages that exhibit remarkable genetic stability. These results indicate that a predatory viral-microbial dynamic, manifest in a number of other characterized environmental ecosystems, is notably absent in the very distal intestine.

Nature. 2010 Jul 15;466(7304):334-8.

Why is this cool?
Viruses. 'Nuff said.

 If that isn't enough for you, let me explain. The researchers collected fecal matter three times a year from three people: identical twins and the mother of those twins. Then they isolated the DNA from that feces and sequenced it (did they sequence it all? Or just the 16S ribosomal RNA sequences? I don't know yet). They determined what each sequence was and then compared the sequences from each person to each other person. As you know, identical twins have the exact same genome sequence, but mothers only share ~50% genome sequence.

The results show that each person regardless of genetic similarity has their own unique combination of phages (bacterial viruses). In case you didn't know, our intestines are filled with bacteria that provide us many benefits. Amazing, right?
 I find this immensely amazing because if you look at the human with an eye towards our parasites or passengers, it seems to me that WE ARE AN ECOSYSTEM!! Bacteria fill our bowels. Bugs eat our eyelashes. Our skin is covered in bacteria that provide many benefits as well. I don't know the literature at all, but I wonder if someone has done work on determining the number of human, not bacterial, viruses in us at any time. Also, how many bacteria float in our blood?
 I'm starting to see the world as a nesting doll of ecosystems (what constitutes an ecosystem?). First, we have planet Earth! Next, we have North America! Then, we have Alabama! Smaller, we have Huntsville! Smaller, we have a guy eating at a Subway! Next, we have his bowels! In his bowels are bacteria waving the American flag!!